One-pot synthesis of arginine modified hydroxyapatite carbon microsphere composites for efficient removal of U(Ⅵ) from aqueous solutions

Uranium was not only the main source of nuclear energy but also one of the long-lived radionuclide.Herein, a novel arginine modified hydroxyapatite carbon microsphere composites(defined as C@HAp/Arg) obtained promptly via a one-step mild hydrothermal method, was applied to remove U(Ⅵ) from aqueous solutions. Based on the characterization of transmission electron microscopy(TEM), scanning electron microscopy(SEM), Fourier transformed infrared spectroscopy(FT-IR), X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS), the synthesized C@HAp/Arg presented globular morphology and abundant functional groups(e.g., —COO^-), which were beneficial to its combination with U(Ⅵ). The interaction mechanism and removal capability of U(Ⅵ) on C@HAp/Arg were studied by batch adsorption technique and spectroscopy analysis. The results implied that U(Ⅵ) can form strong surface complexes on C@HAp/Arg. The kinetics adsorption of U(Ⅵ) followed pseudo-second-order kinetic model with high removal efficiency($95% within 5h at pH 5.0). The adsorption isotherms were well fitted by Langmuir model, implying that U(Ⅵ) uptake on C@HAp/Arg was monolayer coverage. It was found that the maximum adsorption capacities of CSs, C@HAp and C@HAp/Arg toward U(Ⅵ) were calculated to be 23.16,72.09 and 569.66 mg/g, respectively, at 298.15 K and pH 5.0, and thermodynamic parameters revealed that the adsorption processes of U(Ⅵ) were spontaneous and endothermic. In addition, effect of co-existed ions and CO_3^(2-)concentrations demonstrated that U(Ⅵ) adsorption on C@HAp/Arg was weakly interfered by foreign ions and carbonate concentrations. More importantly, the adsorption performance of U(Ⅵ) on C@HAp/Arg was still over $87% after five cycles. Therefore, it was noted that the versatile C@HAp/Arg could be potentially used as a powerful building block for the enrichment and disposal of U(Ⅵ) from aqueous solutions, which could efficiently reduce the potential toxicity of U(Ⅵ) in the U(Ⅵ)-contaminated water.

Uranium was not only the main source of nuclear energy but also one of the long-lived radionuclide. Herein, a novel arginine modified hydroxyapatite carbon microsphere composites （defined as C@HAp/ Arg） obtained promptly via a one-step mild hydrothermal method, was applied to remove U（Ⅵ） from aqueous solutions. Based on the characterization of transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, Fourier transformed infrared spectroscopy （FT-IR）, X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XP5）, the synthesized C@HAp/Arg presented globular morphology and abundant functional groups （e.g., -COO^-）, which were beneficial to its combination with U（Ⅵ）. The interaction mechanism and removal capability of U（VI） on C@HAp/Arg were studied by batch adsorption technique and spectroscopy analysis. The results implied that U（Ⅵ） can form strong surface complexes on C@HAp/Arg. The kinetics adsorption of U（Ⅵ） followed pseudo-second-order kinetic model with high removal efficiency （-95% within 5 h at pH 5.0）. The adsorption isotherms were well fitted by Langmuir model, implying that U（Ⅵ） uptake on C@HAp/Arg was monolayer coverage, It was found that the maximum adsorption capacities of CSs, C@HAp and C@HAp/Arg toward U（Ⅵ） were calculated to be 23.16, 72.09 and 569.66 rag/g, respectively, at 298.15 K and pH 5.0, and thermodynamic parameters revealed that the adsorption processes of U（Ⅵ） were spontaneous and endothermic. In addition, effect of co-existed ions and CO3^2- concentrations demonstrated that U（Ⅵ） adsorption on C@HAp/Arg was weakly interfered by foreign ions and carbonate concentrations. More importantly, the adsorption performance of U（Ⅵ） on C@HAp/Arg was still over -87% after five cycles. Therefore, it was noted that the versatile C@HAp/Arg could be potentially used as a powerful building block for the enrichment and disposal of U（Ⅵ） from aqueous solutions, which could efficiently reduce the potential toxicity of U（Ⅵ） in the U （Ⅵ）-contaminated water.